I really like this story topic and where it's headed but there are grammatical errors that make it hard to read. Maybe you could proof read it some more or get a friend too? But i'm really loving the plot! :D
Keep it up!

I like were your going with this story so far. :)
At first I thought your title said "My sisters Best Friend" lol but when I started reading your story I got what the title actually meant. "My Sisters Boyfriend". Wow flash on me. Lol. I like your story